In recent years, more and more attention has been paid to the concepts of environmental conservation. As the light-emitting diode (Light Emitting Diode, LED) lighting technology continues to progress, LED's luminous efficiency has gone beyond the conventional lighting device, and therefore LED lighting is widely used in various applications such as LED headlamp, LED searchlight, LED projecting lamp, LED decorative lighting, etc.
For conventional LED lamps, to control the variation of the luminescence and color of an LED at specific position, it usually needs additional signal transmission lines and a control circuit, which are costly and complicated. In addition, since the conventional LED lights are disposed in series, if anyone of the LED lights or the integrated circuit does not work, unless the failure can be found and fixed, the entire LED lighting device can not be functioning.
Please refer to FIG. 1, which is a schematic diagram showing an LED lighting series module 10 according to the prior art. The traditional LED lighting series module 10 includes a power converter 101 and a plurality of LED units 102 connected in series. The power converter 101 includes a micro controller 1010, and converts a commercial power AC1 into a first voltage VDC1 between terminals V+ and V− so as to support the plurality of LED units 102. The power converter 102 also converts the commercial power AC1 into a second voltage VDC2 so as to support the micro controller 1010, which is electrically connected to a first LED unit 1021 via a first signal line 103. The first LED unit 1021 is electrically connected to a second LED unit 1022 via a second signal line 104. Likewise, a required number of LED units to be connected in series can be achieved. The micro controller 1010 provides a control signal SC1 to control the first LED unit 1021, while the first LED unit transmits a control signal SC2 to the second LED unit 1022 in response to the first control signal SC1. Likewise, control signals can be transmitted to each of the LED unit in series.
The aforementioned method for driving the LED units may respectively control the lighting status, such as illuminating, dim or flickering, of each of the LED units SC1, SC2, . . . , SCn by conveying the control signals to each of LED units, respectively. However, the method needs additional data lines provided for the control, and there exist delays of the control signals SC2, . . . , SCn, which therefore derives the delay issues in addition to the complexity thereof.
In the application documents of Taiwan Model Patent No. M343822, which provides a two-wired AC LED light serial circuit, LED control signals are transmitted via AC power to control the dim/light of specific LED light of the same color. However, the control signal must be transmitted within a particular period of time which is the zero crossing of AC voltage. That is, both the power supply signal and the control signal coexist with the use of time division. Transmitting control signals in this manner result in low efficiency, because the transfer control signal is subject to the frequency of the commercial power, e.g., usually 60 Hz, and the transmission time period of the AC voltage is also restricted by the specific time period of zero-crossing zone.
In summary, the prior art includes the following drawbacks:    1. The whole series of LED units cannot be used if one of the LED units in the LED series is burnt out.    2. There exist delays of the control signals, and the control signals cannot be received at the same time.    3. The transmission time period of the AC voltage is restricted by the specific time period of zero-crossing zone.    4. The control signal according to the prior art can only control the dim/light of the LED of the same color.
In order to overcome the drawbacks in the prior art, an LED circuit and a driving method for the LED circuit, and more particularly an LED circuit capable of generating different luminescence as well as color variations and a driving method for the LED circuit is provided. The novel design in the present invention not only solves the problems described above, but also is easy to be implemented. Thus, the present invention has utility for the industry.